Draw tape bags have been commercially available for several years. For example, draw tape or draw cord bags are generally described in U.S. Pat. Nos. 2,798,523, 3,029,853, 3,506,048 and 3,687,357. Draw tape bags are formed by employing two pliable plastic sheets joined on three sides (or a U-folded plastic sheet joined on two sides) and open on the remaining side. A tubular hem is provided at the open edge of each sheet and contains a cord(s) or pliable thermoplastic strip(s). One or more access holes are provided in the tubular hem to expose the cord(s) or strip(s), so as to facilitate pulling the cord(s) or strip(s) through the opening(s). The action of pulling the cord(s) or strip(s) through the opening results in both closing the open mouth of the bag and formation of a handle whereby the bag may be carried by means of the cord(s) or strip(s).
The manufacture of multilayer films has been disclosed in the patent literature for several years, but there has not been a disclosure or teaching as to the use of a multilayer material as a draw tape in a draw tape bag. A multilayer trash bag film is disclosed in U.S. Pat. No. 4,511,609 wherein the film comprises a first outer layer of low pressure, low density polyethylene, a core layer of high pressure, low density polyethylene, and a second outer layer of high pressure, low density polyethylene. U.S. Pat. No. 4,126,262 discloses an all-plastic heat sealable container material comprising a core layer of high density thermoplastic polymeric material having a specific gravity of about 0.950 to about 0.965, having a thickness of 15 mils to 17.5 mils and outer layers of a lower density thermoplastic polymeric material having a specific gravity of about 0.918 to about 0.930, a thickness of about 0.75 mils to about 2.0 mils and characterized as having a lower softening point. The multiple layer composite blank may be formed using a core layer of high density polyethylene and the outer layers may be formed of low density polyethylene, as shown in the examples beginning at column 10, line 39. The low softening point of the outside layers permits heat sealing while the core layer is not significantly thermally affected. The thickness of the core layer (15 mils to 17.5 mils) provides structural support to the container. U.S. Pat. No. 4,390,573 discloses laminar thermoplastic films having a first layer of low density polyethylene bonded to a layer of a dissimilar polymer blend comprising high density polyethylene and polyethylene copolymers. As is clear from the above discussion, the above discussed patents do not relate to draw tape bags and the unique problems associated with the strength of the draw tape and its sealability to relatively thin pliable bag forming materials.